Ultramulsion based oral care rinse compositions

ABSTRACT

The present invention relates to various oral care rinses containing, stable, dispersions of certain high viscosity silicones in certain surfactants; wherein: 
     a. the dispersed silicones, which are insoluble in said surfactant, are oriented by the surfactant such that when dispersed in water they are particularly adept at forming oriented, coatings on surfaces of the mouth with enhanced substantivity, and 
     b. the particle size of the dispersed silicone is from between about 0.1 and about 10 microns, with a particle size distribution such that from between about 80 and 95% of the dispersed silicone is within this particle size range. These stable dispersions are described as ULTRAMULSION™ dispersions, which, together with their physical properties, when contained in oral care rinses, provide these rinses with enhanced substantivity to mouth surfaces, where the non continuous silicone phase functions as a reservoir for various active ingredients contained therein, including but not limited to an essential mixture of thymol, eucalyptol, menthol and methyl salicylate.

BACKGROUND OF THE INVENTION

The present invention relates to a unique oral care rinse compositionscontaining a dispersion of certain silicones in certain surfactants.When added to water these dispersions are stable and are distinct fromsolutions, emulsions and microemulsions. These dispersions are referredto hereinafter as ULTRAMULSION™ dispersions. This trademark is theproperty of Whitehill Oral Technologies, Inc. For further informationregarding ULTRAMULSION™ dispersions, see copending application Ser. No.08/144,778, now U.S. Pat. No. 5,538,667, the disclosure of which ishereby incorporated herein by reference. See also copending patentapplication Ser. Nos. 08/462,613; 08/462,203; 08/462,600; 08/463,010;08/461,698; 08/464,403; and 08/462,599; all filed on Jun. 5, 1996, thedisclosures of which are hereby incorporated by reference.

The ULTRAMULSION™ dispersion based oral care rinses of the presentinvention exhibit unique and unexpected substantivity to oral surfacesincluding teeth and gums while providing a reservoir for various lipidsoluble, essential oil, active ingredients resulting in antiplaque,antibacterial, antigingivitis benefits that last for extended periods.This combination of enhanced substantivity and the reservoir effectdescribed in detail below are further combined with excellent particlesize to provide optimum coatings to the oral cavity.

Other oral care products containing the ULTRAMULSION™ dispersions of thepresent invention include: spray, gels, creams, toothpastes, toothpowders, denture cleaning tablets, dental floss, interproximalsimulators, mints, and chewing gums. These products are described andclaimed in the referenced copending patent applications.

The compositions of the present invention may be used by dentists andhygienists in various professional oral hygiene treatments and/or may beused by consumers in various at-home oral hygiene programs withoutprofessional supervision.

As to Antiplaque Benefits:

The present invention further relates to the interference with theformation of plaque. Plaque is a microbial coating on tooth surfaces,bound together by natural polymers (e.g., mucopolysaccharides) formed bymicrobial action on the cell debris, food remnants, sugars and starchesin the mouth. Embedded in this polymer matrix are the bacteria normal tothe oral cavity but, when trapped against tooth surfaces and protectedby the matrix from easy removal, are in excellent position for"mischief." Most dental texts implicate plaque in the formation ofcaries, or tooth decay. In addition, these embedded bacteria releasetoxins that cause gingivitis, bleeding and swelling of the gums.Gingivitis can lead to periodontitis in which gums recede, pockets ofinfection form and teeth loosen.

Plaque formation is an ongoing process. Various other mouth rinse andmouth pre-rinse preparations make antiplaque, and/or antigingivitisclaims. One disadvantage of these preparations is that only a relativelyshort time during which the teeth are being cleaned or the mouth isbeing rinsed is available for these preparations to take effect. Forexample, see the "Transport Kinetics Ethanol and Sorbitol Effects"Listerine® and Listerine® Coolmint as discussed below. Thesepreparations generally have little residual effect on plaque formation.

Effective oral hygiene requires that three control elements bemaintained by the individual:

1. Physical removal of stains, plaque and tartar.

This is accomplished in the strongest sense by scraping and abrasion inthe dentist's office. Self administered procedures are requiredfrequently between visits and range from tooth brushing with anappropriate abrasive toothpaste through flossing and water jet actiondown to certain abrasive foods and even the action of the tongue againsttooth surfaces.

2. Surfactant Cleansing.

This is required to remove: food debris and staining substances beforethey adhere to the tooth surfaces; normal dead cellular (epithelial)material which is continually sloughed off from the surfaces of the oralcavity and microbial degradation products derived from all of the above.Besides the obvious hygienic and health benefits related to simplecleanliness provided by surfactants, there is an important cosmetic andsense-of-well-being benefit provided by surfactant cleansing. Researchhas shown that the primary source of bad breath is the retention andsubsequent degradation of dead cellular material sloughed offcontinuously by the normal, healthy mouth.

3. Frequency of Cleansing.

This is perhaps the most difficult to provide in today's fast-paced workand social environment. Most people recognize that their teeth should bebrushed at least 3 times a day plus after each snacking occasion, andrinsed twice a day.

The simple fact is that most of the population brush once a day, somebrush morning and evening, but precious few carry toothbrush anddentifrice to use the other three or four times a day for optimal oralhygiene. Consumer research suggests that the population brushes anaverage of 1.2 times a day. Thus, the 24 hour period between brushingsfor a majority of the population provides optimum plaque formingconditions with no interruptions. Less than half of the population rinseonce a day.

Since plaque is regarded by most of the dental profession as a causativeagent leading to various dental pathologies as noted above, there isconsiderable desire by most consumers to disrupt or prevent theformation of plaque on a daily basis. There are three oral carestrategies which address the problem of plaque: abrasion, antimicrobialagents and removal of precursors to plaque.

1. Abrasive removal of the plaque film, once it has firmly adhered tothe tooth surface, is the only totally effective cleansing mechanism.Again, professional dental hygiene is the most effective, but recently anumber of special abrasive toothpastes have been accepted by dentalorganizations as partially removing adhered plaque and the tartar whichsubsequently forms from the plaque.

2. Antimicrobial action could affect plaque formation in two ways, (a)reducing the number of bacteria in the mouth which form themucopolysaccharides and (b) killing those bacteria trapped in the filmto prevent further growth and metabolism.

3. Removal of plaque precursors requires the reduction of food sourcesand building blocks required for the bacteria to synthesize themucopolysaccharides which polymerize into the plaque film. Going farback into the chain of events leading to plaque formation andinterrupting the chain has much to commend it as a sound oral hygienestrategy. However, for this strategy to be effective, the plaquebuilding blocks must be interrupted periodically. As noted above,heretofore, the oral hygiene preparations described above fall short on"frequency-of-use" basis.

For reference see: L. Menaker, The Biologic Basis of Dental Caries,Chapters 5, 11, 12, 14, 16 and 18, Harper & Row (1980). See also U.S.Pat. Nos. 4,465,661; 3,507,955; 4,902,497; 4,661,341; 4,666,708;4,537,778; 4,657,758; 3,624,120; 4,525,342; 4,476,107; 5,078,988;2,806,814; 4,774,077; 4,612,191; 4,353,890; 4,894,220; British Pat. No.689,679, Gatter et al., Journal of Pharmaceutical Sciences, 74:1228-1232 (1985); and Bass, Dent. Items of Interest, 70: 921-34 (1948).

As to Anti-Gingivitis Benefits:

It is generally accepted that antimicrobial substances are mosteffective in responding to gingivitis flare ups/infections of the gums.Suitable antimicrobials include stannous fluoride, as described in: U.S.Pat. Nos. 5,057,308; 5,057,309; 5,057,310 and in the FDA filingresponsive to the Sep. 19, 1990 call-for-data (55 Fed. Reg. 38560) filedby WhiteHill Oral Technologies Jun. 17, 1991, Docket 81N-0033, OTC210246 to 210262 and 210339 and specifically the "Annotated Bibliographyset out in Vol. VI of said filing.

Other anti-gingivitis antimicrobials include chlorhexidine, halogenateddiphenyl ethers such as triclosan, phenol and its homologs and theessential oils used in Listerine®. U.S. Pat. Nos. 4,022,880 and4,894,220 disclose and claim various triclosan based oral care products.U.S. Pat. No. 4,894,220 includes an extensive teaching on phenol and itshomologs suitable as antimicrobial agents. Metronidazole is discussed indetail in U.S. Pat. No. 4,568,535. The Listerine® essential oils aredescribed in detail by Kornman in Journal of Periodontal Research,Supplement 1986: 5-22 (1986).

Other anti-plaque active ingredients include:

a. Quaternary ammonium compounds including benzethonium chloride,cetylpyridinium chloride as described by Volpe et al., Journal of DentalResearch, 48: 832-841 (1969) and Gjermo et al., Journal of PeriodontalResearch, 5: 102-109 (1970).

b. Phenolic compounds including the mixture of thymol, eucalyptol,menthol along with methyl salicylate described as "essentials oils" inListerine®. See Fornell et al., Scandinavian Journal of Dental Research,83: 18-25 (1975), Lusk et al., Journal of the American Society ofPreventive Dentistry, 4: 31-37 (1974); Gomer et al., Journal of theAmerican Society of Preventive Dentistry, 2: 12-14 (1972).

As to Periodontitis Benefits:

The main cause of tooth loss in adults is periodontal disease. Yet,surprisingly, less than one percent of the public expenditures fordental treatment is for periodontal disease (see J. Dent. Educ., 43: 320(1979). This is because conventional periodontal treatment is tooexpensive for most individuals, mainly due to the labor intensive,symptomatic treatment that is usually performed by highly skilledspecialists.

Periodontal disease is an all-inclusive term for a variety of clinicalentities that are forms of either gingivitis or periodontitis.Gingivitis is an inflammation of the gingiva or gums that can beassociated with poor oral hygiene and/or hormonal states of the host. Itis assumed, but not proven in the human, that gingivitis will progressto periodontitis, which is the form of the disease in which theinfection has progressed to involve the oral tissues which retain theteeth in the jaw bone. Periodontitis is the more severe form of thedisease, and if untreated, will eventuate in the loss of the tooth.

Dentists have long assumed that periodontal disease originates by theovergrowth of bacteria on the tooth surfaces in aggregates known asdental plaque. If this plaque persists for long periods of time on thetooth surfaces, it may in some instances calcify, forming the hardsubstance known as calculus. Numerous studies describe chemical agentswhich can in vitro and in vivo reduce plaque formation and calculus.However, none of these chemical agents has been reported to besuccessful in treating periodontitis.

A substantial number of different types of compounds and compositionshave been developed for use as antibacterial and antiplaque agents,e.g., benzethonium chloride and cetyl pyridinium chloride, disclosed inU.S. Pat. No. 4,110,429, or as anticalculus agents, e.g.,2-phosphono-butane 1,2,4-tricarboxylic acid, disclosed in U.S. Pat. No.4,224,308. These compounds are designed to be used by the individual indentifrices, dental powders, pastes, mouthwashes, nonabrasive gels,chewing gums, topical solutions and the like, e.g., see U.S. Pat. No.4,205,061. They are designed to be used as prophylactic agents, usuallywithout requiring a prescription or supervision during usage, e.g., seeU.S. Pat. No. 4,251,507. Often they are compounded with detergents andother cleaning agents, and this cleaning action is often an importantaspect of the invention, e.g., see U.S. Pat. Nos. 4,251,507 and4,205,061.

Recent research in periodontal disease (see, for example, Chemotherapyof Dental Plaque Infections, Oral Sci. Rev., 9: 65-107 (1976) indicatesthat gingivitis and periodontitis are characterized by different typesof bacteria. Gingivitis is associated with the accumulation of Grampositive cocci and actinomyces, whereas periodontitis is characterizedby proportional increases in anaerobic bacteria, such as spirochetes andblack pigmented bacteroides (see "Host-Parasite Interactions inPeriodontal Disease," R. J. Genco and S. E. Mergenhagen, eds. Amer. Soc.for Microbiol. Washington, D.C. p. 27-45, 62-75, 1982). The differentbacterial compositions of plaque associated with either gingivitis orperiodontitis suggest that a mode of treatment that is effective ingingivitis may not be effective in periodontitis. Previous discoveriesin the area of periodontal disease have assumed that there is nobacterial specificity in periodontal disease. This is now known to beincorrect. These bacterial differences in plaque may explain why anagent effective in plaque control, such as chlorhexidine, has littleeffect on gingivitis and no published effect on periodontitis.

Another important finding from recent periodontal research is that thecomposition of the dental plaque will differ according to its locationon the tooth surface. Above the gingival or gum margin, facultativebacteria, such as Gram positive cocci and rods, are numericallydominant, whereas below the gum margin, anaerobic motile bacteria suchas spirochetes, and anaerobic Gram negative rods including theblack-pigmented bacteroides are predominant. In other words, twodifferent microbial ecosystems are present on the same tooth surface.

Periodontal disease is a condition caused by a pathogenic microbialecology established within the gingival sulcus which deepens to become aperiodontal pocket. This microbial ecology, located deep within theperiodontal pocket, differs greatly from that of the superficial oralenvironment by being more anaerobic, having a larger number of Gramnegative organisms, and having a greater proportion of motile species.

Several factors impede the diffusion of medicinal agents when applied tothe superficial periodontal tissues. Anatomically, the gum tissue isclosely adapted to the neck of the teeth, mechanically restricting thediffusional pathway. In addition, a fluid termed gingival crevice fluid,with the approximate composition of plasma, permeates the periodontalenvironment and is continually produced by the diseased periodontaltissues at a rate of 10 to 100 microliters per hour. This fluid,emanating from the diseased pocket lining, creates a net outward flowfurther impeding the introduction of medications from superficiallyapplied drug delivery devices. These interferences are sufficientlyeffective to insulate the pocket environment to the extent that salivadoes not penetrate, and topically applied medicinal agents such asrinses have been found largely ineffectual in the treatment ofestablished periodontitis, because of their relatively short "residual"time on mouth surfaces.

Although mouth rinses may be effective in the reduction of gingivitisresulting from poor home care procedures, heretofore the effectiveradius of action of these agents does not extend to the periodontalpocket. Traditionally, introduction of antibacterial agents in solutionform into the periodontal pocket is similarly ineffective due to therapid clearance of such agents so that the duration of contact at theactive site has been minimal.

Conventional therapy for periodontal disease, as first enunciated byPierre Fauchard in 1746 in his book entitled "The Surgeon Dentist, aTreatise on Teeth," involves the mechanical removal of bacterial plaquesand accumulations from the periodontal pocket at periodic intervals.This may include periodontal surgery to achieve access and to recontourdamaged tissues. These procedures require a high degree of technicalexpertise from the practitioners of the art, are expensive, and oftenresult in pain, extensive bleeding, and general discomfort on the partof the patient so treated. Since these procedures provide, at best, onlytemporary reduction in bacterial populations, they must be repeated atregular intervals to be effective. As discussed by Lindhe and coworkersin "Healing Following Surgical/Non-Surgical Treatment of PeriodontalDisease" in the Journal of Clinical Periodontology, Vol. 9, pages115-128, the frequency of repetition needed for optimal results may beas high as once every two weeks.

Methods for administering drugs for periodontal therapy have heretoforelargely been concerned with superficial application. For example,long-acting capsules or tablets held in the mouth (see U.S. Pat. No.3,911,099); buccal implants for releasing drugs into the saliva (seeU.S. Pat. No. 4,020,558); topically applied gels (see U.S. Pat. No.3,679,360); topically applied drug-containing bandages (see U.S. Pat.No. 3,339,546); a drug-containing plastic hardenable mass (see U.S. Pat.No. 3,964,164); a medicated periodontal dressing (see U.S. Pat. No.3,219,527); a topical dressing composed of a finely divided particulatecarrier and suspended medicinal agents (see U.S. Pat. No. 3,698,392); abandage for covering moist mucosal surfaces (see U.S. Pat. No.3,339,546); a microencapsulated liquid droplet formation for topicalapplication to the gums of dogs and other animals (see U.S. Pat. No.4,329,333); and foam-film devices containing medication (see U.S. Pat.No. 3,844,286). In addition, several fibrous forms for superficialmedication have been described, including impregnated or drug-releasingforms of dental floss (see U.S. Pat. Nos. 3,417, 179, 2,667,443,2,748,781, and 3,942,539); solid absorbable fibers of polyglycolic acidwith medicants incorporated therein (see U.S. Pat. No. 3,991,766); andcellulose acetate hollow fibers (see U.S. Pat. No. 4,175,326). See alsoU.S. Pat. No. 4,892,736.

It has been reported in deliberations before a Food and DrugAdministration (FDA) Panel evaluating plaque and gingivitis claimingingredients (see 55 Fed. Reg. 38560) that ethanol at 36.9% is requiredto solubilize the combination of lipophilic antimicrobial actives:eucalyptol at 0.9%, thymol at 0.63%, methyl salicylate at 0.55% andmenthol at 0.055%; in order to transport these activities into thedental plaque biofilm within the recommended 30 second rinse period.

Specifically, in vitro biofilm studies have established that Listerine'salcohol diffuses from a region of higher concentration into the dentalplaque biofilm, transporting the lipophilic antimicrobial essentialoils. These Listerine® transport kinetics (See FIG. 8) allow Listerine®to achieve the impressive antiplaque and antigingivitis clinical effectsas reported for this rinse in the literature.

The FDA is presently deliberating the safety of high level ethanolcontaining mouth rinses, i.e., above 25% ethanol. The need forcomparable antiplaque and antigingivitis rinses containing the essentialoil actives at lower alcohol levels is particularly critical in view ofthe extensive "safety" deliberations underway at the FDA for high levelethanol rinses.

All of the foregoing references and the references cited in thesereferences are incorporated in the description of the present invention.

SUMMARY OF THE INVENTION

The present invention is directed to oral care rinses containing,stable, dispersions of certain high viscosity silicones in certainsurfactants; wherein:

a. the dispersed silicones, which are insoluble in said surfactant, areoriented by the surfactant such that when dispersed in water they areparticularly adept at forming oriented, coatings on surfaces of themouth with enhanced substantivity, and

b. the particle size of the dispersed silicone is from between about 0.1and about 10 microns, with a particle size distribution such that frombetween about 80 and 95% of the dispersed silicone is within thisparticle size range. These stable dispersions are described asULTRAMULSION™ dispersions, which, together with their physicalproperties, when contained in oral care rinses, provide these rinseswith enhanced substantivity to mouth surfaces, where the non continuoussilicone phase functions as a reservoir for various active ingredientscontained therein, including but not limited to an essential mixture ofthymol, eucalyptol, menthol and methyl salicylate.

It has been surprisingly found that certain ULTRAMULSION™ dispersions,i.e., those of the present invention, provide various oral care rinseswith improved antiplaque and antigingivitis, and like performance atreduced ethanol levels. This performance is attributed to: (a) theirenhanced substantivity, (b) the reservoir effect achieved bysolubilizing various lipid soluble, essential oil, active ingredients inthe discontinuous silicone phase of the ultramulsion and (c) thegenerally small particle size of the dispersed silicone phase to effectsuitable coatings in the oral cavity upon rinsing.

It is thus an object of the present invention to provide ULTRAMULSION™dispersion based antiplaque, antigingivitis and periodontal treatmentrinses with an ethanol level below 10% and with enhanced substantivitywhile containing a reservoir of various active essential oil, activeingredients for treating various oral hygiene conditions.

It is another object of the invention to provide a method formanufacturing the low ethanol content the ULTRAMULSION™ dispersion basedoral care rinses of the invention.

It is yet another object of the invention to provide a method to treatvarious oral hygiene conditions with the low alcohol level ULTRAMULSION™dispersion containing rinses of the present invention.

It is another object of the present invention to provide low alcohollevel ULTRAMULSION™ dispersion based oral care rinses with improved oralcare coating properties.

It is also an object of this invention to provide an ULTRAMULSION™dispersion for water based oral care rinses without the need to resortto use of complex high energy processes.

It is a further object of the present invention to provide low ethanollevel ULTRAMULSION™ dispersion based oral care rinses wherein variouslipid soluble, essential oil actives are released from the ULTRAMULSION™dispersion coating into the oral cavity over an extended period.

It is another object of the invention to enhance the biofilm transportkinetics of certain essential oils in oral rinses with reduced ethanollevels.

These and other objects will become readily apparent from the detaileddescription which follows.

Unless otherwise indicated, all percentages and ratios herein are byweight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the "coiled" molecular configuration proposed forpolydimethylsiloxanes;

FIG. 2 illustrates the proposed molecular configuration of orientedpolydimethylsiloxanes after ULTRAMULSION™ dispersion processing;

FIG. 3 illustrates schematically an ULTRAMULSION™ dispersion process ofthe invention;

FIGS. 4 and 5 illustrate that the ULTRAMULSION™ dispersions of theinvention produced via various high shear dispersing means havingparticle size distribution of 80+% under 10 microns;

FIGS. 6 and 7 are a graph and a chart respectively showing the effect ofincreased silicone viscosity on plaque building in a certain oral careproduct; and FIG. 8 illustrates the transport kinetics for certainexcellent oils at various levels of ethanol.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The ULTRAMULSION™ dispersions of the present invention are distinct fromother emulsions as will become apparent from the following:

When a system consists of a single liquid phase it is described as asolution. A system containing two or more liquid phases is described asa multiphase solution or emulsion.

According to Becher, an emulsion is an unstable heterogeneous system inwhich the diameters of the dispersed droplets in general exceed 100 Å.Becher P. in "Emulsions, Theory & Practice," (P. Becher, Ed.) page 2,Rheinhold, New York 1965.

A more comprehensive definition of emulsion is advanced by Clayton: "Anemulsion is a system containing two liquid phases, one of which isdispersed as globules in the other. The liquid which is broken up intoglobules is termed the dispersed or discontinuous phase, while theliquid surrounding the globules is known as the continuous phase ordispersing medium" Clayton, W., "The Theory of Emulsions and TheirTechnical Treatment," 4th Ed. page 1, the Blakiston Co., Philadelphia,1943. It is well accepted that, mechanical work is required to affectsuch an emulsion, see Bancroft W. D., J. Phys. Phy. Chem., 17: 501(1913).

According to Prince, an emulsion may be defined as a dispersion of two(or more) mutually insoluble liquids, one in the other. Because of thesurface tension forces at play between the two liquids, the dispersedphase consists of spherical droplets. Prince, L. M. in "MicroemulsionTheory & Practice," pg. 2, Academic Press Inc., New York, N.Y. (1977).See also Prince, L. N. in "biological Horizons in Surface Science," pg.361, Academic Press Inc. (1973).

Emulsions are generally not stable upon standing or after centrifugingtend to separate into two or more liquid layers.

The three definitions of emulsions set forth above share one commonattribute, that is, mechanical work must be put into the emulsionsdescribed in order to disperse one liquid in the other in the form ofdroplets. This mechanical work can be in the form ofagitation,homogenization, ultrasonication, etc.

In contrast, dispersions of very small droplet sizes which are formedspontaneously without the input of any mechanical work are calledmicroemulsions. See Prince 1977, p. 3. Generally, two surfactants areused in forming microemulsions, i.e., a water soluble surfactant and aco-surfactant such as alcohol, where one phase of the microemulsion isgenerally water. This, dilution or adulteration of the dispersed phaseby the co-solvent generally accompanies microemulsion formation. Theratio of surfactant to dispersed phase in microemulsions is much higherthan that of emulsions. Microemulsions are further characterized asoptically clear or opalescent and when spun in a laboratory centrifugefor 5 minutes at 100 G's, the dispersion remains stable and does notseparate.

Thus, fine particles sizes, exceptional stability and rheologicalproperties that can be easily adjusted, distinguish microemulsions fromemulsions. Moreover, to date, no microemulsions have appeared which oneof the mutually insoluble liquids is not water. See Prince, page 34,(1977).

The ULTRAMULSION™ dispersion based oral care rinses of the presentinvention combine certain characteristics of emulsions with certainfeatures of microemulsions. That is, like emulsions, they are two phasesystems comprising a silicone dispersed in a continuous, surfactantphase, wherein the silicone is insoluble in the surfactant. Unlikeemulsions, but like microemulsions, these dispersions are stable. Unlikemicroemulsions, but like emulsions, mechanical work is required to formultramulsions. Unlike microemulsions, but like emulsions, theseULTRAMULSION™ dispersions are not formed spontaneously. Like emulsions,the ULTRAMULSION™ dispersions do not contain a cosolvent commonly foundin microemulsions. Of course, the ULTRAMULSION™ dispersions of thepresent invention can be dispersed in various liquids such as water asstable dispersions. These ULTRAMULSION™ dispersions have excellentutility in various rinse oral care products. See various examples belowand the various tables below.

While not wishing to be bound by theory, it is hypothesized that unlikeeither emulsions or microemulsions, the dispersed silicones of theULTRAMULSION™ dispersions of the present invention are uniquely orientedwith their polar moieties in one general plane and their hydrophilicmoieties in a plane approximately opposite that of the polar moieties.This orientation promotes stability as well as bonding between the polaror hydrophilic moieties and various surfaces in the oral cavity therebyeffecting oriented, monolayer coatings of the silicone onto thesesurfaces. These oriented dispersions of silicones have a surprisingbroad range of utility in oral care rinses as detailed in the variousexamples below. This orienting is illustrated in FIGS. 1 and 2.

The emulsifying effects of uncoiling of the silicone molecule with theoxygen moieties generally oriented in one plane distinct from that ofthe organo moieties as illustrated in FIGS. 1 and 2, are furthersubstantiated by the following references: Eur. Poly. J., 26: 654(1990); J. Chem. Phys., 49: 1398 (1965); J. Chem. Phys., 54:5011 (1971);J. Chem. Phys., 59: 3825 (1973); Macromolecules, 7: 229 (1974);Macromolecules, 11: 627 (1978) and "Rubber-Like Elasticity: A MolecularPrimer," J. Mark, New York, Wiley-Interscience, 1988.

Methods of preparing polyorganosiloxane emulsions with an averageparticle size of less than about 0.3 microns and polyorganosiloxanemicroemulsions with an average particle size of less than about 0.14micron are described in U.S. Pat. No. 4,620,878. Preparation ofoil-in-water microemulsions are described in U.S. Pat. No. 4, 146,499.Specific surface active compositions used as emulsifiers withdiorganopolysiloxanes to form transparent microemulsions are describedin U.S. Pat. Nos. 4,0562,331 and 3,975,294. U.S. Pat. No. 3,433,780teaches the preparation of colloid silane suspensions. See also"Chemistry and Technology of Silicones," W. Noll, pp. 428 to 431 (1968);Journal of Society of Cosmetic Chemists, 25: 609-619 (1974) and Journalof Colloid & Interface Science, 44: 242-248 (1973).

Miceliar dispersions, microemulsions, transparent emulsions aredescribed in detail in "Annals of the New York Academy of Science,"Shulman & Montagne (1961); U.S. Pat. No. 2,356,205, "The Theory ofEmulsions & Their Technical Treatment," 5th Edition, 1954, U.S. Pat.Nos. 3,497,006; 3,506,070, 3,254,714 and 3,307,628.

The aqueous-free ULTRAMULSION™ dispersions of silicones in surfactantsin low alcohol level rinses containing essential oil antimicrobials asdescribed herein are neither taught nor suggested by the foregoingreferences.

Referring to the drawings, FIG. 1 illustrates the accepted "coiled"configuration advanced for polydimethylsiloxanes, wherein the methylmoieties are oriented outward while the oxygen moieties are orientedinward towards the axis of the coil or helix. This configuration doesnot readily promote "bonding" between the oxygen moieties and compatiblesurfaces such as those in the oral cavity.

FIG. 2 illustrates the "uncoiled oriented" configuration proposed forpolydimethylsiloxanes that have been dispersed in the stable,ULTRAMULSION™ dispersion of the present invention, wherein the oxygenmoieties are generally oriented in one plane distinct from that of themethyl moieties. This proposed uncoiled oriented configuration appearsto support the unique and unexpected stability "bonding and enhancedsubstantivity" properties of the ULTRAMULSION™ dispersion of the presentinvention, as evidenced by the various coating applications of theseULTRAMULSION™ dispersions to surfaces in the oral cavity. See thevarious examples provided below.

FIG. 3 illustrates the ULTRAMULSION™ dispersion process of the presentinvention wherein a nonionic surfactant and a polydimethylsiloxane 1,substantially free from water and co-solvent, are mixed in vessel 2,provided with mixing means 3, heat source 4, and inert head space 5. Theheated and mixed surfactant and poly-dimethylsiloxane 6, is thensubjected to high shear dispersion at an elevated temperature indispersing means 7, to produce the ULTRAMULSION™ dispersion 8, of theinvention.

FIG. 4 is a chart describing the particle size distribution of anULTRAMULSION™ dispersion of the invention containing 95-5% by weightnonionic surfactant and 5-50% by weight polydimethylsiloxane (2.5million cs) produced in a continuous process with an IKA Work dispersingmeans, (high shear dispersing) with an inlet temperature of 140° C. andan outlet temperature of 210° C.

FIG. 5 is a chart describing the particle size distribution of anULTRAMULSION™ dispersion of the invention containing 95-50% by weightnonionic surfactant and 5-50% by weight polydimethylsiloxane (2.5million cs) produced in a batch process with a Ross M/E 100 LCdispersing means fitted with a 20 mesh screen, operated at a temperaturefrom 120°to 160° C.

FIGS. 6 and 7 disclose the influence of increasing viscosity of thesilicone in the ULTRAMULSION™ dispersion on the anti-plaque effect ofthis ULTRAMULSION™ dispersion when introduced into the oral cavityseveral times throughout the day as a mint.

FIG. 8 discloses the transport kinetics for the four essential oilcombination used in Listerine®, wherein the essential oils are presentedin vitro to a dental plaque biofilm and the amount of substancediffusing in time across a plane of area is directly proportional to thechange in concentration with distance traveled. (Fick's First Law).

The limited time window of effectiveness established for an essentialoil rinse containing 26.9% ethanol, is 30 seconds. See FIG. 8 and thepresentation by F. A. Volpe to the FDA Plaque Subcommittee, June 1994.In contrast, the ULTRAMULSION™ based, essential oil rinses of thepresent invention containing 10% and less ethanol (See the Examples ofTable 2) are predicted to support clinical antiplaque and antigingivitisresults comparable to a 26.9% ethanol rinse. Such results would becontrary to the transport kinetics for an essential oil rinse containing26.9% ethanol as shown in FIG. 8. These surprising and unobvious resultsfor the rinse of the invention are attributed to:

1. the enhanced substantivity of the ULTRAMULSION™ dispersion basedcoating;

2. the coating which is comprised of small sized dispersed siliconeparticles, and/or

3. the "reservoir effect" of the silicone coating for the essentialoils.

Specifically, it is suggested that the dispersed silicone phase appearsto release the lipid soluble essential oils for prolonged periods fromthe highly substantive coating of ULTRAMULSION™ dispersion formed in theoral cavity. That is, these lower alcohol level MICRODENT® ULTRAMULSION™dispersion based rinses are not limited to the 30 second window and thetransport kinetics advanced for high level alcohol rinses.

The ULTRAMULSION™ dispersions of the present invention can be includedin traditional oral care rinses, at low alcohol levels, to enhance theanti-plaque and/or anti-gingivitis performance of such products asdescribed in detail in the examples below.

These same ULTRAMULSION™ dispersions contain lipid soluble and lipiddispersible active ingredients in the dispersed silicone phase andthereby impart extended anti-plaque, anti-gingivitis and/oranti-periodontia effects to various rinses. This "reservoir" effect ofsilicones containing active ingredients was documented with the lipidsoluble antimicrobial by Rolla et al., in clinical studies reported inScand. J. Dent. Res., 101: 130-138.

The ULTRAMULSION™ dispersion containing the essential oils has thepotential to be effective in treating periodontal pockets similar to theactive ingredients as described by Genco in J. Periodontology, 52:545-558 (1981) and U.S. Pat. No. 4,892,736 and "Medical Applications ofControlled Release," CRC Press, Boca Raton 1984.

Heretofore these periodontal pockets were fitted treated by being with"slow release" films etc. containing antimicrobials and/or antibioticsetc. such as described by Goodson in U.S. Pat. No. 4,892,736 and Loeschein U.S. Pat. No. 4,568,535 and the pocket then "packed" with aperiodontal dressing. It is suggested these periopockets can be treatedwith rinses of the present invention containing the ULTRAMULSION™dispersions of the present invention wherein the silicone dispersedphase contains the "essential oils" active ingredient and releases theessential oil from the silicone reservoir coating into the perio pocketover an extended period.

For purposes of the present invention, silicone means a clear, colorlesssubstance containing polyalkylsiloxane polymers with average kinematicviscosities up to 4 million cs. These high viscositypolydimethylsiloxanes have viscosities from between about 2.5 million csand about 4 million cs and beyond including "gum" silicones havingviscosities of 30 to 50 million cs; are particularly preferred for theoral care products, of the present invention. Otherpolydimethylsiloxanes suitable for the present invention include"substituted" water insoluble silicones and mixture's ofpolydiorganosiloxanes and substituted water insoluble silicones.specifically, water soluble silicones are excluded from theULTRAMULSION™ dispersions of the invention. See the various Tablespresented below.

The viscosity of some silicones can be measured by means of a glasscapillary viscometer as set forth in Dow Corning Corporate Test MethodCTM0004, Jul. 20, 1970.

The silicone fluid may be either a high viscosity polyalkyl siloxane asdescribed in detail below. Mixtures of various silicones may also beused and are preferred in certain embodiments of the invention.

The polyether siloxane copolymer that may be used is, for example, apolypropylene oxide modified dimethylpolysiloxane although ethyleneoxide or mixtures of ethylene oxide and propylene oxide may also beused.

References disclosing suitable silicone fluids include U.S. Pat. No.2,826,551 to Green; U.S. Pat. No. 3,964,500 to Drakoff; U.S. Pat. No.4,364,837 to Padner and British Pat. No. 849,433 to Woolston. All ofthese patents are hereby incorporated herein by reference. Alsoincorporated herein by reference is Silicon Compounds distributed byPetrarch Systems, Inc., 1984. This reference provides a very goodlisting of suitable silicone materials.

Silicone materials found especially useful in the present compositionsto provide good oral hygiene results are silicone gums. Silicone gumsdescribed by Petrarch and others including U.S. Pat. No. 4, 152,416, May1, 1979 to Spitzer et al., and Noll, Walter, Chemistry and Technology ofSilicones, New York, Academic Press 1968. Also describing silicone gumsare various General Electric Silicone Rubber Product Data Sheets. All ofthese described references are incorporated herein by reference."Silicone gum" materials denote high molecular weightpolydiorganosiloxanes having a viscosity up to about 50 million cs.Specific examples include polydimethylsiloxane, polydimethylsiloxane,methylvinylsiloxane, copolymer, polydimethylsiloxane, diphenyl,methylvinylsiloxane copolymer and mixtures thereof.

As noted above high viscosity polydimethylsiloxanes i.e., those above100,000 cs are preferred. Particularly preferred arepolydimethylsiloxanes from between about 2.5 million cs and about 50million cs. The safety of polydimethylsiloxanes for use in these variousproducts is well documented. See Rowe et al., Journal of IndustrialHygiene, 30: 332-352 (1948). See also Calandra et al., "ACS PolymerPreprints," 17: 1-4 (1976) and Kennedy et al., J. Toxicol &Environmental Health, 1: 909-920 (1976).

As noted above, preferred polydimethylsiloxanes useful in the oral carecompositions of the present invention are described aspolymethylsiloxanes with the chemical composition:

    (CH.sub.3).sub.3 SiO[SiO(CH.sub.3).sub.3 ].sub.n Si(CH.sub.3).sub.3

wherein n is a whole number. These polydimethylsiloxanes haveviscosities up to 50 million cs. and are generally described as havinghigh molecular weights.

The particle size of the silicone in the ULTRAMULSION™ dispersion of thepresent invention can range from between about 0.1 and about 10 microns.In a preferred embodiment of the present invention the particle size ofpolydimethylsiloxanes in the ULTRAMULSION™ dispersion ranges frombetween about 1 and about 5 microns. The particle size distribution ofthe polydimethylsiloxanes in the ULTRAMULSION™ dispersion of the presentinvention generally range from between about 80 and about 95% of theparticles under 10 microns. See FIGS. 4 and 5. In a preferred embodimentof the present invention, from between about 80 and about 95% of theparticles are under 5 microns.

An essential component of the ULTRAMULSION™ dispersion is a surfactant.The surfactant, may be selected from any of a wide variety of syntheticanionic, amphoteric, zwitterionic and nonionic surfactants, that aresafe for use in the oral cavity.

The surfactants suitable for the purposes of the present invention mustfunction as the continuous phase and contain the disposal discontinuoussilicone phase. Generally, these surfactants are liquid or meltablesubstances and include mixtures of surfactants as detailed in theexamples and tables below. Synthetic anionic surfactants can beexemplified by the alkali metal salts of organic sulfuric reactionproducts having in their molecular structure an alkyl radical containingfrom 8-22 carbon atoms and a sulfonic acid or sulfuric acid esterradical (included in the term alkyl is the alkyl portion of higher acylradicals). Preferred are the sodium, ammonium. potassium ortriethanolamine alkyl sulfates, especially those obtained by sulfatingthe higher alcohols (C₈ -C₁₈ carbon atoms), sodium coconut oil fattyacid monoglyceride sulfates and sulfonates; sodium or potassium salts ofsulfuric acid esters of the reaction product of 1 mole of a higher fattyalcohol (e.g., tallow or coconut oil alcohols) and 1 to 12 moles ofethylene oxide ether sulfate with 1 to 10 units of ethylene oxide permolecule and in which the alkyl radicals contain from 8 to 12 carbonatoms, sodium alkyl glycerol ether sulfonates; the reaction product offatty acids having from 10 to 22 carbon atoms esterified with isethionicacid and neutralized with sodium hydroxide; water soluble salts ofcondensation products of fatty acids with sarcosine; and other known inthe art.

Zwitterionic surfactants can be exemplified by those which can bebroadly described as derivatives of aliphatic quaternary ammonium,phosphonium, and sulfonium compounds, in which the aliphatic radicalscan be straight chain or branched, and wherein one of the aliphaticsubstituents contains from about 8 to 18 carbon atoms and one containsan anionic water-solubilizing group, e.g., carboxyl, sulfonate, sulfate,phosphate, or phosphonate. A general formula for these compounds is:##STR1## wherein R² contains an alkyl, alkenyl, or hydroxyl alkylradical of from about 8 to 18 carbon atoms, from 0 to about 10 ethyleneoxide moieties and from 0 to 1 glycerol moiety; Y is selected from thegroup consisting of nitrogen, phosphorous, and sulfur atoms; R³ is analkyl or monohydroxyalkyl group containing 1 to about 3 carbon atoms; Xis 1 when Y is a sulfur atom and 2 when Y is a nitrogen or phosphorousatom; R⁴ is an alkylene or hydroxyalkylene of from 1 to about 4 carbonatoms and Z is a radical selected from the group consisting ofcarboxylate, sulfonate, sulfate, phosphonate, and phosphate groups.

Examples include:

4-[N,N-di(2-hydroxyethyl)-N-octadecylammonio]-butane-1-carboxylate;

5-(S-3-hydroxypropyl-S-hexadecylsulfonio]-3-hydroxypentane-1-sulfate;

3-[P,P-diethyl-P-3,6,9-trioxatetradexocylphosphonio]-2-hydroxypropane-1-phosphate;

3-[N,N-dipropyl-N-3-dodecoxy-2-hydroxypropylammonio]-propane-1-phosphate;

3-[N,N-dimethyl-N-hexadecylammonio-propane-1-sulfonate;

4-[N,N-di(2-hydroxyethyl)-N-(2-hydroxydodecyl)ammonio]-butane-1-carboxylate;

3-[S-ethyl-S-(3-dodecoxy-2-hydroxypropyl)sulfonio]-propane-1-phosphate;

3-[P,P-dimethyl-P-dodecylphosphonio]-propane-1-phosphonate; and

5-(N,N-di(3-hydroxypropyl)-N-hexadecylammonio]-2-hydroxypentane-1-sulfate.

Other zwitterionics such as betaines are also useful in the presentinvention. Examples of betaines useful herein include the higher alkylbetaines such as cocodimethyl carboxymethyl betaine, lauryl dimethylcarboxymethyl betaine, lauryl dimethyl alpha-carboxyethylene betaine,cetyl dimethyl carboxymethyl betaine, laurylbis-(2-hydroxy-ethyl)carboxy methyl betaine, stearylbis-(20-hydroxypropyl)-carboxymethyl betaine, oleyl dimethylgamma-carboxypropyl betaine, laurylbis-(2-hydroxypropyl)alpha-carboxyethyl betaine, etc. The sulfobetainesmay be represented by cocodimethyl sulfopropyl betaine, stearyl dimethylsulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, laurylbis-(2-hydroxy-ethyl)sulfopropyl betaine and the like; amido betainesand amidosulfo betaines, wherein the RCONH(CH₂)₃ radical is attached tothe nitrogen atom of the betaine are also useful in this invention. Theamido betaines are preferred for use in some of the compositions of thisinvention. A particularly preferred composition utilizes an amidobetaine, a quaternary compound, a silicone, a suspending agent and has apH of from about 2 to about 4.

Examples of amphoteric surfactants which can be used in theULTRAMULSION™ dispersion of the present invention are those which can bebroadly described as derivatives of aliphatic secondary and tertiaryamine in which the aliphatic radical can be straight chain or branchedand wherein one of the aliphatic substituents contains from about 8 toabout 18 carbon atoms and one contains an anionic water solubilizinggroup, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate.Examples of compounds falling within this definition are sodium3-dodecylamino-propionate, sodium 3-dodecylamino-propane sulfonate,N-alkyltaurines such as the one prepared by reacting dodecylamine withsodium isethionate according to the teaching of U.S. Pat. No. 2,658,072,N-higher alkyl aspartic acids such as those produced according to theteaching of U.S. Pat. No. 2,438,091, and the products sold under thetrade name "Miranol" and described in U.S. Pat. No. 2,528,378.

Nonionic surfactants, which are preferably used in combination with ananionic, amphoteric or zwitterionic surfactant, can be broadly definedas compounds produced by the condensation of alkylene oxide groups(hydrophilic in nature) with an organic hydrophobic compound, which maybe aliphatic or alkyl aromatic in nature. Examples of preferred classesof nonionic surfactants are:

1. The polyethylene oxide condensates of alkyl phenols, e.g., thecondensation products of alkyl phenols having an alkyl group containingfrom about 6 to 12 carbon atoms in either a straight chain or branchedchain configuration, with ethylene oxide, the said ethylene oxide beingpresent in amounts equal to 10 to 60 moles of ethylene oxide per mole ofalkyl phenol. The alkyl substituent in such compounds may be derivedfrom polymerized propylene, disobutylene, octane, or nonane, forexample.

2. Those derived from the condensation of ethylene oxide with theproduct resulting from the reaction of propylene oxide andethylenediamine products which may be varied in composition dependingupon the balance between the hydrophobic and hydrophilic elements whichis desired. For example, compounds containing from about 40% to about80% polyoxyethylene by weight and having a molecular weight of fromabout 5,000 to about 15,000 resulting from the reaction of ethyleneoxide groups with a hydrophobic base constituted of the reaction productof ethylene diamine and excess propylene oxide, said base having amolecular weight of the order of 2,500 to 3,000 are satisfactory.

3. The condensation product of aliphatic alcohols having from 8 to 18carbon atoms, in either straight chain or branched chain configuration,with ethylene oxide, e.g., a coconut alcohol ethylene oxide condensatehaving from 10 to 30 moles of ethylene oxide per mole of coconutalcohol, the coconut alcohol fraction having from 10 to 14 carbon atoms.

4. Long chain tertiary amine oxides corresponding to the

following general formula: ##STR2## wherein R₁ contains an alkyl,alkenyl or monohydroxy alkyl radical of from about 8 to about 18 carbonatoms from 0 to about 10 ethylene oxide moieties, and from 0 to 1glycerol moiety, and R₂ and R₂ contains from 1 to about 3 carbon atomsand from 0 to about 1 hydroxy group, e.g., methyl, ethyl, propyl,hydroxy ethyl, or hydroxypropyl radicals. The arrow in the formula is aconventional representation of a semipolar bond. Example of amine oxidessuitable for use in this invention include dimethyl-dodecylamine oxide,oleyldi(2-hydroxy-ethyl) amine oxide, dimethyloctylamine oxide,dimethyl-decylamine oxide, dimethyltetradecylamine oxide.3,6,9-trioxaheptadecyldiethylamine oxide, di)2-hydroxyethyl)-tetracylamine oxide, 2-dodecoxyethyldimethylamine oxide,3-dodecoxy-2-hydroxypropyldi-(3-hydroxy-propyl)amine oxide,dimethylhexadecylamine oxide.

5. Long chain tertiary phosphine oxides corresponding to the followinggeneral formula: ##STR3## wherein R contains an alkyl, alkenyl ormonohydroxyalkyl radical ranging from 8 to 18 carbon atoms in chainlength from 0 to about 10 ethylene oxide moieties and from 0 to 1glycerol moiety and R' and R" are each alkyl or monohydroxyalkyl groupscontaining from 1 to 3 carbon atoms. The arrow in the formula is aconventional representation of a semipolar bond. Examples of suitablephosphine oxides are: dodecyldimethylphosphine oxide,tetradecyl-dimethylphosphine oxide, tetradecyl-methylethylphosphineoxide. 3,6,9-trioxaoctadecyldimethylphosphine oxide,cetyldimethylphosphine oxide,3-dodecoxy-2-hydroxypropyl-di(2-hydroxyl)-phosphine oxide,stearyldimethylphosphine oxide, cetylethylpropylphosphine oxide,cetyldiethylphosphine oxide, dodecyl-diethylphosphine oxide,tetradecyl-diethylphosphine oxide, dodecyldipropylphosphine oxide,dodecyldi(2-hydroxyethyl) phosphine oxide,tetradecyl-methyl-2-hydroxydodecyldimethylphosphine oxide.

6. Long chain dialkyl sulfoxides containing one short chain alkyl orhydroxy alkyl radical of 1 to about 3 carbon atoms (usually methyl) andone long hydrophosphic chain which contain alkyl, alkenyl, hydroxyalkyl, or keto alkyl radicals containing from about 8 to about 20 carbonatoms, from 0 to about 10 ethylene oxide moieties and from 0 to 1glycerol moiety. Examples include: octadecyl menthyl sulfoxide,2-ketotridecyl methyl sulfoxide, 3,6,9,-trioxooctadecyl 2-hydroxyethylsulfoxide, dodecyl menthyl sulfoxide, oleyl 3-hydroxypropyl sulfoxide,tetradecyl menthyl sulfoxide, 3-methoxytridecyl methyl sulfoxide,3-hydroxytridecyl methyl sulfoxide, 3-hydroxy-4-dodecoxy-butyl methylsulfoxide.

Many additional nonsoap surfactants are described in McCUTCHEON'S,DETERGENTS AND EMULSIFIERS, 1979 ANNUAL, published by Allured PublishingCorporation which is incorporated herein by reference.

Particularly preferred nonionic surfactants are nonionic poloxamersurfactants of block copolymers of ethylene oxide and propylene oxideranging from flowable liquids of varying viscosities, to paste, prillsand cast solids with molecular weights from 1,100 to 150,000. Suitablenonionic surfactants are manufactured and marketed by BASF Corporationunder the trademarks Pluronic. Particularly preferred nonionicsurfactants are Pluronic F-68, F-88, F-108 and Pluronic F-127. These aredescribed in a BASF brochure entitled "Pluronic and Tetronic BlockCopolymer Surfactant." These nonionic surfactants suitable for thepresent invention can be described by the following structure: ##STR4##where x, y and x' are whole numbers. Surprisingly, the nonionicsurfactants of choice for the ULTRAMULSION™ dispersion of the presentinvention are reported in the referenced brochure to have marginaldetergency, emulsification and wetting properties. See Tables 1 and 2.

As noted above, the preferred nonionic poloxamer surfactants useful inthe coating compositions of the present invention are described aspolyoxyethylene-polyoxypropylene block copolymers such as Pluronic F-68,F-88, F-108 and F-127 (BASF) which have molecular weights of at leastabout 1000 such as described in U.S. Pat. Nos. 4,343,785, 4,465,663,4,511,563 and 4,476,107, the disclosures of which are herebyincorporated herein by reference.

Emulsions of various coating substances including polydimethylsiloxanesin various surfactants including nonionic surfactants are disclosed andclaimed in U.S. Pat. Nos. 4,911,927, 4,942,034; 4,950,479; 5,009,881;5,032,387; 5,057,306; 5,057,307; 5,057;308, 5,057,309; 5,057,310,5,098,711, 5,165,913 and 5,284,648. There is no teaching in thesereferences that these highly viscosity silicone emulsions are stable northat the "coating" substances are oriented as they are in theULTRAMULSION™ dispersions of the present invention, not that coatings ofthe ULTRAMULSION™ dispersions comprised of silicones from 0.1 to 10microns are as substantive as they are, nor that the dispersed siliconephase would function as a reservoir through lipid soluble essential oil.

The ratio of surfactant to silicone in the ULTRAMULSION™ dispersioncoating compositions of the present invention can range from betweenabout 400:1 and about 1:2. In a preferred embodiment of the inventionthe ratio of surfactant to silicone is from between about 25:1 and 1:2.See Tables 1 and 2.

For the purposes of the present invention:

a. stable is defined as, dispersion of the ULTRAMULSION™ dispersion inwater when subjected to centrifuging in a 100 G environment for 5minutes, less than about 10% by weight of the ULTRAMULSION™ dispersionseparates from the continuous water phase and/or a substantial portionof the dispersed phase resists separation. This latter definition isparticularly applicable to higher viscosity silicones. See Table 2.

b. water-free means, that the ULTRAMULSION™ dispersion of silicone andsurfactant is substantially free from water.

c. solvent free means, that the ULTRAMULSION™ dispersion of silicone andsurfactant is substantially free from co-solvents such as ethanol,isopropanol, etc.

d. oriented means, that the polar moieties of the "uncoiled"polydimethylsiloxane in the ULTRAMULSION™ dispersion are generallyaligned in one plane with the hydrophilic oil seeking moieties alignedin a second plane such as illustrated in FIG. 2.

e. monolayer means, that the monomolecular film of the ULTRAMULSION™where the silicone phase is of the particle size described above and thedispersion of the invention, when dispersed in water, is attracted tomucosa and hydroxyapatite by secondary bonding forces to form asubstantive coating thereon.

f. essential oil is defined as a combination of lipophilic antimicrobialactives at various concentrations comprising: eucalyptol, preferably at0.091% thymol, preferably at 0.063%, methyl salicylate, preferably at0.055% and menthol, preferably at 0.55%.

f. transport kinetics enhancer is defined as a substance other thanalcohol that accelerates essential oil diffusion into dental plaquebiofilm wherein the essential oil is soluble in said transport kineticsenhancer.

h. antimicrobial adjunct is defined as a liquid soluble or lipiddispersible antimicrobial that augments the antimicrobial effect of theessential oil and is present in either the dispersed or continuoushydroalcohol phase.

METHOD OF MANUFACTURE

The various oral care products of the present invention can be made bymixing the materials together and heating if necessary and followingaccepted manufacturing practices for these various products as describedin detail below.

For instance, preferred ULTRAMULSION™ dispersions of the presentinvention are prepared as follows:

Generally, if not a liquid, the surfactant is heated to a temperature atwhich it becomes a liquid. The silicone is dispersed in the heatedsurfactant with various high shear dispersing means.

Specifically the heated surfactant is mechanically stirred along withthe silicone to form a pre-emulsion mixture in which the silicone isuniformly dispersed in the surfactant in droplets of a larger size thendesired for the ULTRAMULSION™ dispersion but small enough to optimizethe subsequent high shear dispersions. This mixture is subjected tohigh-shear dispersions with a means such as the IKA-WORKS DISPAX-Reactorwith at least one superfine generator, alternatively, a Ross Model M.E., 100 LC fitted with a 20 mesh screen or a ultrasonicator such asMEDSONIC XL2010 fitted with 800-C Flow Cell & 800-21CT 3/4 inch flangedhorn can be used.

The rinses of the present invention can be alcohol-free or contain up toabout 10% by weight ethanol and or ethanol up to 10% plus polyhydricpolyols such as sorbitol and various polyols.

Various ULTRAMULSION™ dispersions containing which are prepared andanalyzed are described in detail in the examples below.

                  TABLE I                                                         ______________________________________                                        ORAL CARE                                                                     % W/W                                                                         Example No.                                                                              1     2     3   4   5   6   7   8   9   10  11                     ______________________________________                                        Component                                                                     Dimethicone                                                                   viscosity-                                                                    centistokes                                                                     100,000  10    --    --  --  --  --  --  --  --  33  --                       600,000  --    10    --  --  --  --  33  --  --  --  --                      2,500,000 --    --    10  --  --  --  --  33  --  --  10                      4,000,000 --    --    --  10  --  --  --  --  33  --  --                     30,000,000 --    --    --  --  10  --  --  --  --  --  --                     50,000,000 --    --    --  --  --  10  --  --  --  --  --                     Poloxamer - 188                                                                          --    --    --  --  --  --  --  --  --  67  --                     Poloxamer - 238                                                                          --    --    --  --  --  --  --  --  --  --  90                     Poloxamer - 338                                                                          90    90    90  90  90  90  --  --  --  --  --                     Poloxamer - 407                                                                          --    --    --  --  --  --  67  67  67  --  --                     ______________________________________                                    

Specific poloxamer/polydimethylsiloxane ULTRAMULSION™ dispersionssuitable for use with various oral care products were prepared andanalyzed as described in Table 2 below:

                                      TABLE 2                                     __________________________________________________________________________    ORAL CARE                                                                     % W/W                                                                         Example No.                                                                             12  13  14 15 16 17 18 19 20 21                                     __________________________________________________________________________    Component                                                                     Dimethicone                                                                   viscosity-centistokes                                                           600,000 --  11.6                                                                              -- -- -- 10.0                                                                             -- -- -- --                                      2,500,000                                                                              10.0                                                                              --  -- 11.9                                                                             11.9                                                                             -- -- -- -- 14.0                                    4,000,000                                                                              --  --  11.6                                                                             -- -- -- -- -- 10.0                                                                             --                                     30,000,000                                                                              --  --  -- -- -- 11.6                                                                             -- -- -- --                                     50,000,000                                                                              --  --  -- -- -- -- 11.6                                                                             10.0                                                                             -- --                                     Lipid Soluble                                                                 Component                                                                     Mixture Of:                                                                   Thymol    0.063                                                                             0.063                                                                             1.0                                                                              2. 3  4  .1 .2 .3 .4                                     Menthol   0.055                                                                             0.55                                                                              1.0                                                                              2. 3  4  .1 .2 .3 .4                                     Eucalyptol                                                                              0.091                                                                             0.91                                                                              1.0                                                                              2. 3  4  .1 .2 .3 .4                                     Methyl Salicylate                                                                       0.055                                                                             0.55                                                                              1.0                                                                              2. 3  4  .1 .2 .3.                                                                              .4                                     Surfactant                                                                    Poloxamer 338                                                                           89.76                                                                             85.76                                                                             84.4                                                                             80.1                                                                             76.4                                                                             74.0                                                                             88.0                                                                             89.2                                                                             88.8                                                                             84.4                                   __________________________________________________________________________

The discontinuous silicone phase of the ULTRAMULSION™ dispersion canalso contain a wide range of other lipid soluble and/or lipiddispersible oral care active ingredients ranging from otherantimicrobials to desensitizing/substances, to healants such as aloe tovitamins such as vitamin E, to flavorants, etc. These variousingredients in the silicone phase of the ULTRAMULSION™ dispersionperform in various oral care products as though they are contained in a"reservoir" as they continue to be available at the ULTRAMULSION™dispersion oral surface interface, as long as the ULTRAMULSION™dispersion coating remains substantive to mouth surfaces. Similareffects attributed to this reservoir effect are described by Rolla etal., supra.

The oral care rinses containing the ULTRAMULSION™ dispersions of thepresent invention will contain a variety of essential components rangingfrom other surfactants for cleaning, to other flavorants etc.

Water is an essential component of oral care rinse products of thepresent invention which contain one or more of the various ULTRAMULSION™dispersions described above. The water in these rinses is generallypresent at a level of from about 80% to about 95%, preferably frombetween about 85% and about 90%.

In addition these oral care rinses can contain a variety of nonessentialoptional components suitable for rendering such compositions moreacceptable.

Such conventional optional ingredients are well known to those skilledin the art, e.g., preservatives such as benzyl alcohol, methyl paraben,propyl paraben and imidiazolidinyl urea; cationic surfactants such ascetyl trimethylammonium chloride, lauryl trimethyl ammonium chloride,tricetyl methyl ammonium chloride, stearyldimethyl benzyl ammoniumchloride, and di(partially hydrogenated tallow)dimethylammoniumchloride; thickeners and viscosity modifiers such as diethanolamide of along chain fatty acid (e.g., PEG 3 lauramide), block polymers ofethylene oxide and propylene oxide such as Pluronic F88 offered by BASFWyandotte, sodium chloride, sodium sulfate, polyvinyl alcohol, and ethylalcohol; pH adjusting agents such as citric acid, succinic acid,phosphoric acid, sodium hydroxide, sodium carbonate, etc., perfumes;dyes; and, sequestering agents such as disodium ethylenediaminetetraacetate. Such agents generally are used individually at a level offrom about 0.01% to about 10%, preferably from about 0.5% to about 5.0%by weight of the composition. The pH of the present compositions ispreferably from about 6 to 8.

The present invention has been described in detail, including thepreferred embodiments thereof. However, it will be appreciated thatthose skilled in the art, upon consideration of the present disclosure,may make modifications and/or improvements on this invention and stillbe within the scope and spirit of this invention as set forth in thefollowing claims.

What is claimed is:
 1. An oral care rinse composition wherein saidcomposition comprises an aqueous-free high shear ULTRAMULSIONdispersion, formed by heating a mixture of surfactant and silicone,followed by high shear mixing wherein:a. the silicone is insoluble insaid surfactant, has a viscosity of greater than about 100,000 cs and aparticle size up to about 10 microns; b. the surfactant to siliconeratio in the ULTRAMULSION dispersion is from between about 400:1 andabout 1:1; and the surfactant has an orienting effect on the silicone;c. the ULTRAMULSION dispersion forms stable dispersions in aqueouscontaining oral care rinse compositions, and d. said rinse compositionexhibits enhanced substantivity to surfaces in the oral cavity while thedispersed silicone phase of said ULTRAMULSION dispersion functions as areservoir for additional lipid soluble and lipid dispersible oral careactive ingredients, selected from the group consisting of essentialoils, triclosan, chlorhexidine phenol and its homologs, metronidazole,quaternary ammonium compounds and mixtures thereof.
 2. The oral carerinse composition according to claim 1, wherein said ULTRAMULSIONdispersion comprises a nonionic poloxamer surfactant andpolydimethylsiloxane wherein:a. said polydimethylsiloxane has thechemical formula (CH₃)₃ SiO[SiO(CH₃)₂ ]_(n) Si(CH₃)₃, wherein n is awhole number; b. said surfactant has the chemical formula ##STR5##wherein x, y, and x' are whole numbers; C, the viscosity of thepolydimethylsiloxane ranges from between about 2.5 million and about 50million cs; d. the particle size of most of the polydimethylsiloxane inthe ULTRAMULSION dispersion is from between about 0.1 and about 10microns; e. from between about 80% and 95% of said polydimethylsiloxaneparticles in the ULTRAMULSION dispersion are from between about 1 andabout 10 microns; f. the nonionic surfactant is apolyoxyethylene-polyoxypropylene block copolymer having a molecularweight from between about 1,100 and about 150,000; g. the ratio ofsurfactant to polydimethylsiloxane is from between about 400:1 and about1:2; and h. wherein the ULTRAMULSION dispersion as dispersed in analcohol-free water based oral care rinse composition is stable.
 3. Amethod of manufacturing ULTRAMULSION dispersions suitable for oral carerinse compositions said method comprising, heating said surfactant andsilicone mixture in a heated, stirred vessel substantially free fromwater, followed by subjecting said mixture to high shear dispersion;wherein:a. the silicone is insoluble in said surfactant, has a viscosityup to about 50 million cs, and a particle size up to about 10 microns,b. the surfactant to silicone ratio in the high shear dispersion is frombetween about 400:1 and about 1:1; and the surfactant has an orientingeffect on the silicone, c. the silicone is oriented, exhibits enhancedsubstantivity to surfaces in the oral cavity and functions as areservoir for various lipid soluble and lipid dispersible hair careactive ingredients.
 4. A method according to claim 3, wherein the heatedvessel is provided with an inert head of gas.
 5. A method according toclaim 3, wherein said high shear dispersing means is fitted with a smallorifice.
 6. A method according to claim 3 wherein said high sheardispersing means comprises ultrasonication means.
 7. A stable aqueousbased oral care rinse composition containing up to 10% ethanol, andhaving dispersed therein an ULTRAMULSION dispersion comprising anonionic poloxamer surfactant and a polydimethylsiloxane insoluble insaid surfactant wherein:a. said polydimethylsiloxane has the chemicalformula (CH₃)₃ SiO[SiO(CH₃)₂ ]_(n) Si(CH₃)₃, wherein n is a wholenumber; b. said surfactant has the chemical formula ##STR6## wherein x,y, and x' are whole numbers; C. the viscosity of thepolydimethylsiloxane ranges from between about 2.5 million and about 50million cs; d, the particle size of most of the polydimethylsiloxane inthe ULTRAMULSION dispersion is from between about 0.1 and about 10microns; e. from between about 80% and 95% of said polydimethylsiloxaneparticles in the ULTRAMULSION dispersions are from between about 1 andabout 10 microns; f. the nonionic surfactant is apolyoxyethylene-polyoxypropylene block copolymer having a molecularweight from between about 1,100 and about 150,000; g. the ratio ofsurfactant to polydimethylsiloxane is from between about 400:1 and about1:2; and h. the ULTRAMULSION dispersion as dispersed in water is stable;and i. wherein the oral care active ingredient is an essential oilmixture containing thymol, eucalyptol, menthol and methyl salicylate. 8.A rinse composition according to claim 7, wherein the ratio of saidsurfactant to said silicone is 9:1 and 90% of the silicone particles arefrom between about 1 and 3 microns.
 9. A rinse composition according toclaim 7, wherein the ratio of said surfactant to said silicone is 2:1and 100% of the silicone dispersion is less than 10 microns.
 10. A rinsecomposition according to claim 7, wherein the ratio of said surfactantto said silicone is 1:1 and the silicone particles in said ULTRAMULSIONdispersion are less than 10 microns.
 11. A rinse composition containingan ULTRAMULSION dispersion comprising a nonionic poloxamer surfactantand polydimethylsiloxane insoluble in said surfactant wherein:a. saidpolydimethylsiloxane has the chemical formula (CH₃)₃ SiO[SiO(CH₃)₂ ]_(n)Si(CH₃)₃, wherein n is a whole number; b. said surfactant has thechemical formula ##STR7## wherein x, y, and x' are whole numbers; c. theviscosity of the polydimethylsiloxane ranges from between about 100,000million and about 4 million cs; d. the particle size of most of thepolydimethylsiloxane in the ULTRAMULSION dispersion is from betweenabout 0.1 and about 10 microns; e. from between about 80% and 95% ofsaid polydimethylsiloxane particles in the ULTRAMULSION dispersion arefrom between about 1 and about 10 microns; f. the nonionic surfactant isa polyoxyethylene-polyoxypropylene block copolymer having a molecularweight from between about 1,100 and about 150,000; g. the ratio ofsurfactant to polydimethylsiloxane is from between about 400:1 and about1:2; h. the ULTRAMULSION dispersion as dispersed in the water basedrinse is stable, and i. the polydimethylsiloxane contains the essentialoil active ingredients, menthol, eucalyptol, thymol and methylsalicylate.
 12. A rinse composition according to claim 7, wherein thesilicone is a polydimethylsiloxane uncoiled and oriented wherein theoxygen moieties are generally oriented in a plane distinct from that ofthe methyl/moieties.
 13. A rinse composition according to claim 1,wherein the physical state of the surfactant is selected from the groupconsisting of, flowable liquids pastes, prills and cast solids.
 14. Amethod according to claim 3, wherein the high shear dispersion isachieved with high shear dispersing means selected from the groupconsisting of superfine dispersion means and ultrasonic dispersionmeans.
 15. A rinse composition according to claim 7, wherein the ratioof surfactant to polydimethylsiloxane is 1:1 and at least 80% of thepolydimethylsiloxane dispersed particles are between 1 and 9 microns.16. A rinse composition according to claim 1, wherein the ratio orsurfactant to polydimethylsiloxane is 9:1 and about 90% of thepolydimethylsiloxane dispersed particles are between 1 and 3 microns.17. A rinse composition according to claim 1, wherein the ratio orsurfactant to polydimethylsiloxane is 2:1 and about 90% of thepolydimethylsiloxane dispersed particles are between 1 and 3 microns.18. A rinse composition according to claim 7, wherein the ratio ofsurfactant to polydimethylsiloxane is 4:1 and about 90% of thepolydimethylsiloxane dispersed particles are between 1 and 9 microns.19. A rinse composition according to claim 7, wherein the ratio ofsurfactant to polydimethylsiloxane is 9.5:0.5 and about 100% of thepolydimethylsiloxane dispersed particles are between 1 and 9 microns.20. A rinse composition according to claim 7, wherein thepolydimethylsiloxane has a viscosity of 2.5 million cs and thesurfactant is a solid at room temperature.
 21. A rinse compositionaccording to claim 1, wherein the silicone further contains an oral careactive ingredient selected from the group consisting of, anti-plaque,anti-tartar, anti-gingivitis and anti-periodontitis active ingredients.22. A rinse composition according to claim 21, wherein the siliconefurther contains triclosan.
 23. A rinse composition according to claim21, wherein the silicone further contains the mixture of essential oilscomprising: thymol at 0.63%, eucalyptol at 9,91%, menthol at 0.55% andmethyl salicylate at 0.55%.
 24. A rinse composition according to claim21, wherein the silicone further contains a quaternary ammoniumcompound.
 25. A rinse composition according to claim 21, wherein thesilicone further contains chlorhexidine.
 26. A rinse compositionaccording to claim 21, wherein the silicone further containsmetronidazole.